qa: enable debug logs for fs:cephadm:multivolume subsuite

This subsuite does not enable client/mds debug logs. Sample:

        https://pulpito.ceph.com/vshankar-2024-05-10_15:47:15-fs-wip-vshankar-testing-20240509.114851-debug-testing-default-smithi/7701509/

which is a failed run - it would have been better to have debug
logs for the same.

Fixes: http://tracker.ceph.com/issues/66029
Signed-off-by: Venky Shankar <[email protected]>

Author: vshankar

qa/suites/fs/cephadm/multivolume/conf

@@ -0,0 +1 @@
+.qa/cephfs/conf